Concentrating solar power (CSP) offers a clean, endless, and reliable source of energy with potentially unlimited capacity. CSP plants have many advantages over other types of power plants, one of the most notable being that CSP plants produce little to no carbon dioxide emissions. As a result, many countries, including the United States, have begun integrating CSP into their national supply grids through large-scale commercial plants.
CSP plants produce power by concentrating sunlight to heat water and produce steam. The steam then rotates a turbine connected to a generator, or other conventional device, thereby producing electricity. Currently, there are four types of CSP technologies, including: parabolic troughs, dish/engine systems, linear Fresnel reflectors, and power towers. Parabolic trough technology uses parabolic mirrors to concentrate sunlight onto a linear receiver pipe positioned along the mirrors' focal line. Because this technology was the first CSP technology, it is the most developed and commonly used technology. Dish/engine systems use a parabolic mirror to focus sunlight on a receiver placed at the mirror's focal point. These systems are smaller and may be used to generate power for smaller applications, such as for a single building. Linear Fresnel reflector technology is similar to parabolic trough technology, except that it uses flat mirrors that reflect sunlight onto water-filled pipes that generate steam. This technology often has a cost advantage over parabolic trough technology because flat mirrors are usually less expensive to produce than parabolic mirrors. Finally, power tower systems typically use flat mirrors to reflect the sun's rays onto a receiver located at the top of a central tower, often three to five hundred feet tall.
A problem with existing CSP technology is the complex array of components that must be assembled for the system to operate. Typically, the assembly of the system must be accomplished in the field. In the case of power tower technology, existing systems consist of a receiver mounted on top of a structural steel tower having box sections, diagonal bracing, etc. Many of the towers have as many as three to four thousand pieces of steel that must be assembled in the field. In addition, the rest of the system generally requires a single tube or pipe, or an assembly of pipes in the form of a piped manifold. The pipes are interconnected with receiver panels and a drum. These must be field erected using a significant number of piping components to be installed atop the large structural steel tower. Such a project often requires thousands of hours of labor or more and is very expensive.
In view of the problems noted above, there is a need for improved CSP systems that may require less in-field assembly and that may also efficiently collect solar radiation. The present invention addresses these needs and more.
The present invention provides a solar energy system that includes a tower having a solar radiation receiver, the solar radiation receiver including a plurality of tubes carrying a heat-transfer medium and a drum, where the drum is in thermal communication with the tubes. The solar energy apparatus further includes one or more mirrors configured to reflect solar radiation onto the receiver. The receiver receives the reflected solar radiation from the mirrors, thereby heating the heat transfer medium and vaporizes the heat transfer medium.
The present invention further provides a method of generating power from sunlight using the above described system, the method including focusing sunlight on a convex solar radiation receiver attached to a tower, the receiver being in the al communication with a heat transfer medium such that focused sunlight heats and vaporizes the heat transfer medium, and employing the vaporized heat transfer medium in a turbine generator to produce power.
The present invention also provides a solar energy system that includes a tower having a substantially convex solar radiation receiver attached thereto, and a plurality of mirrors arranged circumferentially around the tower and configured to focus sunlight onto the receiver, wherein the receiver includes a plurality of tubes carrying a heat transfer medium, the tubes configured to accept radiation from the sunlight reflected on the receiver and heat the heat transfer medium and vaporize the heat transfer medium within the receiver.